/****************************************************************************
 *
 * Copyright 2016 Samsung Electronics All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific
 * language governing permissions and limitations under the License.
 *
 ****************************************************************************/

/*
 *  CTR_DRBG implementation based on AES-256 (NIST SP 800-90)
 *
 *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); you may
 *  not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *  This file is part of mbed TLS (https://tls.mbed.org)
 */
/*
 *  The NIST SP 800-90 DRBGs are described in the following publucation.
 *
 *  http://csrc.nist.gov/publications/nistpubs/800-90/SP800-90revised_March2007.pdf
 */

#include "tls/config.h"

#if defined(MBEDTLS_CTR_DRBG_C)

#include "tls/ctr_drbg.h"

#include <string.h>

#if defined(MBEDTLS_FS_IO)
#include <stdio.h>
#endif

#if defined(MBEDTLS_SELF_TEST)
#if defined(MBEDTLS_PLATFORM_C)
#include "tls/platform.h"
#else
#include <stdio.h>
#define mbedtls_printf printf
#endif							/* MBEDTLS_PLATFORM_C */
#endif							/* MBEDTLS_SELF_TEST */

/* Implementation that should never be optimized out by the compiler */
static void mbedtls_zeroize(void *v, size_t n)
{
	volatile unsigned char *p = v;
	while (n--) {
		*p++ = 0;
	}
}

/*
 * CTR_DRBG context initialization
 */
void mbedtls_ctr_drbg_init(mbedtls_ctr_drbg_context *ctx)
{
	memset(ctx, 0, sizeof(mbedtls_ctr_drbg_context));

#if defined(MBEDTLS_THREADING_C)
	mbedtls_mutex_init(&ctx->mutex);
#endif
}

/*
 * Non-public function wrapped by mbedtls_ctr_drbg_seed(). Necessary to allow
 * NIST tests to succeed (which require known length fixed entropy)
 */
int mbedtls_ctr_drbg_seed_entropy_len(mbedtls_ctr_drbg_context *ctx, int (*f_entropy)(void *, unsigned char *, size_t), void *p_entropy, const unsigned char *custom, size_t len, size_t entropy_len)
{
	int ret;
	unsigned char key[MBEDTLS_CTR_DRBG_KEYSIZE];

	memset(key, 0, MBEDTLS_CTR_DRBG_KEYSIZE);

	mbedtls_aes_init(&ctx->aes_ctx);

	ctx->f_entropy = f_entropy;
	ctx->p_entropy = p_entropy;

	ctx->entropy_len = entropy_len;
	ctx->reseed_interval = MBEDTLS_CTR_DRBG_RESEED_INTERVAL;

	/*
	 * Initialize with an empty key
	 */
	mbedtls_aes_setkey_enc(&ctx->aes_ctx, key, MBEDTLS_CTR_DRBG_KEYBITS);

	if ((ret = mbedtls_ctr_drbg_reseed(ctx, custom, len)) != 0) {
		return (ret);
	}

	return (0);
}

int mbedtls_ctr_drbg_seed(mbedtls_ctr_drbg_context *ctx, int (*f_entropy)(void *, unsigned char *, size_t), void *p_entropy, const unsigned char *custom, size_t len)
{
	return (mbedtls_ctr_drbg_seed_entropy_len(ctx, f_entropy, p_entropy, custom, len, MBEDTLS_CTR_DRBG_ENTROPY_LEN));
}

void mbedtls_ctr_drbg_free(mbedtls_ctr_drbg_context *ctx)
{
	if (ctx == NULL) {
		return;
	}
#if defined(MBEDTLS_THREADING_C)
	mbedtls_mutex_free(&ctx->mutex);
#endif
	mbedtls_aes_free(&ctx->aes_ctx);
	mbedtls_zeroize(ctx, sizeof(mbedtls_ctr_drbg_context));
}

void mbedtls_ctr_drbg_set_prediction_resistance(mbedtls_ctr_drbg_context *ctx, int resistance)
{
	ctx->prediction_resistance = resistance;
}

void mbedtls_ctr_drbg_set_entropy_len(mbedtls_ctr_drbg_context *ctx, size_t len)
{
	ctx->entropy_len = len;
}

void mbedtls_ctr_drbg_set_reseed_interval(mbedtls_ctr_drbg_context *ctx, int interval)
{
	ctx->reseed_interval = interval;
}

static int block_cipher_df(unsigned char *output, const unsigned char *data, size_t data_len)
{
	unsigned char buf[MBEDTLS_CTR_DRBG_MAX_SEED_INPUT + MBEDTLS_CTR_DRBG_BLOCKSIZE + 16];
	unsigned char tmp[MBEDTLS_CTR_DRBG_SEEDLEN];
	unsigned char key[MBEDTLS_CTR_DRBG_KEYSIZE];
	unsigned char chain[MBEDTLS_CTR_DRBG_BLOCKSIZE];
	unsigned char *p, *iv;
	mbedtls_aes_context aes_ctx;

	int i, j;
	size_t buf_len, use_len;

	if (data_len > MBEDTLS_CTR_DRBG_MAX_SEED_INPUT) {
		return (MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG);
	}

	memset(buf, 0, MBEDTLS_CTR_DRBG_MAX_SEED_INPUT + MBEDTLS_CTR_DRBG_BLOCKSIZE + 16);
	mbedtls_aes_init(&aes_ctx);

	/*
	 * Construct IV (16 bytes) and S in buffer
	 * IV = Counter (in 32-bits) padded to 16 with zeroes
	 * S = Length input string (in 32-bits) || Length of output (in 32-bits) ||
	 *     data || 0x80
	 *     (Total is padded to a multiple of 16-bytes with zeroes)
	 */
	p = buf + MBEDTLS_CTR_DRBG_BLOCKSIZE;
	*p++ = (data_len >> 24) & 0xff;
	*p++ = (data_len >> 16) & 0xff;
	*p++ = (data_len >> 8) & 0xff;
	*p++ = (data_len) & 0xff;
	p += 3;
	*p++ = MBEDTLS_CTR_DRBG_SEEDLEN;
	memcpy(p, data, data_len);
	p[data_len] = 0x80;

	buf_len = MBEDTLS_CTR_DRBG_BLOCKSIZE + 8 + data_len + 1;

	for (i = 0; i < MBEDTLS_CTR_DRBG_KEYSIZE; i++) {
		key[i] = i;
	}

	mbedtls_aes_setkey_enc(&aes_ctx, key, MBEDTLS_CTR_DRBG_KEYBITS);

	/*
	 * Reduce data to MBEDTLS_CTR_DRBG_SEEDLEN bytes of data
	 */
	for (j = 0; j < MBEDTLS_CTR_DRBG_SEEDLEN; j += MBEDTLS_CTR_DRBG_BLOCKSIZE) {
		p = buf;
		memset(chain, 0, MBEDTLS_CTR_DRBG_BLOCKSIZE);
		use_len = buf_len;

		while (use_len > 0) {
			for (i = 0; i < MBEDTLS_CTR_DRBG_BLOCKSIZE; i++) {
				chain[i] ^= p[i];
			}
			p += MBEDTLS_CTR_DRBG_BLOCKSIZE;
			use_len -= (use_len >= MBEDTLS_CTR_DRBG_BLOCKSIZE) ? MBEDTLS_CTR_DRBG_BLOCKSIZE : use_len;

			mbedtls_aes_crypt_ecb(&aes_ctx, MBEDTLS_AES_ENCRYPT, chain, chain);
		}

		memcpy(tmp + j, chain, MBEDTLS_CTR_DRBG_BLOCKSIZE);

		/*
		 * Update IV
		 */
		buf[3]++;
	}

	/*
	 * Do final encryption with reduced data
	 */
	mbedtls_aes_setkey_enc(&aes_ctx, tmp, MBEDTLS_CTR_DRBG_KEYBITS);
	iv = tmp + MBEDTLS_CTR_DRBG_KEYSIZE;
	p = output;

	for (j = 0; j < MBEDTLS_CTR_DRBG_SEEDLEN; j += MBEDTLS_CTR_DRBG_BLOCKSIZE) {
		mbedtls_aes_crypt_ecb(&aes_ctx, MBEDTLS_AES_ENCRYPT, iv, iv);
		memcpy(p, iv, MBEDTLS_CTR_DRBG_BLOCKSIZE);
		p += MBEDTLS_CTR_DRBG_BLOCKSIZE;
	}

	mbedtls_aes_free(&aes_ctx);

	return (0);
}

static int ctr_drbg_update_internal(mbedtls_ctr_drbg_context *ctx, const unsigned char data[MBEDTLS_CTR_DRBG_SEEDLEN])
{
	unsigned char tmp[MBEDTLS_CTR_DRBG_SEEDLEN];
	unsigned char *p = tmp;
	int i, j;

	memset(tmp, 0, MBEDTLS_CTR_DRBG_SEEDLEN);

	for (j = 0; j < MBEDTLS_CTR_DRBG_SEEDLEN; j += MBEDTLS_CTR_DRBG_BLOCKSIZE) {
		/*
		 * Increase counter
		 */
		for (i = MBEDTLS_CTR_DRBG_BLOCKSIZE; i > 0; i--)
			if (++ctx->counter[i - 1] != 0) {
				break;
			}

		/*
		 * Crypt counter block
		 */
		mbedtls_aes_crypt_ecb(&ctx->aes_ctx, MBEDTLS_AES_ENCRYPT, ctx->counter, p);

		p += MBEDTLS_CTR_DRBG_BLOCKSIZE;
	}

	for (i = 0; i < MBEDTLS_CTR_DRBG_SEEDLEN; i++) {
		tmp[i] ^= data[i];
	}

	/*
	 * Update key and counter
	 */
	mbedtls_aes_setkey_enc(&ctx->aes_ctx, tmp, MBEDTLS_CTR_DRBG_KEYBITS);
	memcpy(ctx->counter, tmp + MBEDTLS_CTR_DRBG_KEYSIZE, MBEDTLS_CTR_DRBG_BLOCKSIZE);

	return (0);
}

void mbedtls_ctr_drbg_update(mbedtls_ctr_drbg_context *ctx, const unsigned char *additional, size_t add_len)
{
	unsigned char add_input[MBEDTLS_CTR_DRBG_SEEDLEN];

	if (add_len > 0) {
		/* MAX_INPUT would be more logical here, but we have to match
		 * block_cipher_df()'s limits since we can't propagate errors */
		if (add_len > MBEDTLS_CTR_DRBG_MAX_SEED_INPUT) {
			add_len = MBEDTLS_CTR_DRBG_MAX_SEED_INPUT;
		}

		block_cipher_df(add_input, additional, add_len);
		ctr_drbg_update_internal(ctx, add_input);
	}
}

int mbedtls_ctr_drbg_reseed(mbedtls_ctr_drbg_context *ctx, const unsigned char *additional, size_t len)
{
	unsigned char seed[MBEDTLS_CTR_DRBG_MAX_SEED_INPUT];
	size_t seedlen = 0;

	if (ctx->entropy_len + len > MBEDTLS_CTR_DRBG_MAX_SEED_INPUT) {
		return (MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG);
	}

	memset(seed, 0, MBEDTLS_CTR_DRBG_MAX_SEED_INPUT);

	/*
	 * Gather entropy_len bytes of entropy to seed state
	 */
	if (0 != ctx->f_entropy(ctx->p_entropy, seed, ctx->entropy_len)) {
		return (MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED);
	}

	seedlen += ctx->entropy_len;

	/*
	 * Add additional data
	 */
	if (additional && len) {
		memcpy(seed + seedlen, additional, len);
		seedlen += len;
	}

	/*
	 * Reduce to 384 bits
	 */
	block_cipher_df(seed, seed, seedlen);

	/*
	 * Update state
	 */
	ctr_drbg_update_internal(ctx, seed);
	ctx->reseed_counter = 1;

	return (0);
}

int mbedtls_ctr_drbg_random_with_add(void *p_rng, unsigned char *output, size_t output_len, const unsigned char *additional, size_t add_len)
{
	int ret = 0;
	mbedtls_ctr_drbg_context *ctx = (mbedtls_ctr_drbg_context *)p_rng;
	unsigned char add_input[MBEDTLS_CTR_DRBG_SEEDLEN];
	unsigned char *p = output;
	unsigned char tmp[MBEDTLS_CTR_DRBG_BLOCKSIZE];
	int i;
	size_t use_len;

	if (output_len > MBEDTLS_CTR_DRBG_MAX_REQUEST) {
		return (MBEDTLS_ERR_CTR_DRBG_REQUEST_TOO_BIG);
	}

	if (add_len > MBEDTLS_CTR_DRBG_MAX_INPUT) {
		return (MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG);
	}

	memset(add_input, 0, MBEDTLS_CTR_DRBG_SEEDLEN);

	if (ctx->reseed_counter > ctx->reseed_interval || ctx->prediction_resistance) {
		if ((ret = mbedtls_ctr_drbg_reseed(ctx, additional, add_len)) != 0) {
			return (ret);
		}

		add_len = 0;
	}

	if (add_len > 0) {
		block_cipher_df(add_input, additional, add_len);
		ctr_drbg_update_internal(ctx, add_input);
	}

	while (output_len > 0) {
		/*
		 * Increase counter
		 */
		for (i = MBEDTLS_CTR_DRBG_BLOCKSIZE; i > 0; i--)
			if (++ctx->counter[i - 1] != 0) {
				break;
			}

		/*
		 * Crypt counter block
		 */
		mbedtls_aes_crypt_ecb(&ctx->aes_ctx, MBEDTLS_AES_ENCRYPT, ctx->counter, tmp);

		use_len = (output_len > MBEDTLS_CTR_DRBG_BLOCKSIZE) ? MBEDTLS_CTR_DRBG_BLOCKSIZE : output_len;
		/*
		 * Copy random block to destination
		 */
		memcpy(p, tmp, use_len);
		p += use_len;
		output_len -= use_len;
	}

	ctr_drbg_update_internal(ctx, add_input);

	ctx->reseed_counter++;

	return (0);
}

int mbedtls_ctr_drbg_random(void *p_rng, unsigned char *output, size_t output_len)
{
	int ret;
	mbedtls_ctr_drbg_context *ctx = (mbedtls_ctr_drbg_context *)p_rng;

#if defined(MBEDTLS_THREADING_C)
	if ((ret = mbedtls_mutex_lock(&ctx->mutex)) != 0) {
		return (ret);
	}
#endif

	ret = mbedtls_ctr_drbg_random_with_add(ctx, output, output_len, NULL, 0);

#if defined(MBEDTLS_THREADING_C)
	if (mbedtls_mutex_unlock(&ctx->mutex) != 0) {
		return (MBEDTLS_ERR_THREADING_MUTEX_ERROR);
	}
#endif

	return (ret);
}

#if defined(MBEDTLS_FS_IO)
int mbedtls_ctr_drbg_write_seed_file(mbedtls_ctr_drbg_context *ctx, const char *path)
{
	int ret = MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR;
	FILE *f;
	unsigned char buf[MBEDTLS_CTR_DRBG_MAX_INPUT];

	if ((f = fopen(path, "wb")) == NULL) {
		return (MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR);
	}

	if ((ret = mbedtls_ctr_drbg_random(ctx, buf, MBEDTLS_CTR_DRBG_MAX_INPUT)) != 0) {
		goto exit;
	}

	if (fwrite(buf, 1, MBEDTLS_CTR_DRBG_MAX_INPUT, f) != MBEDTLS_CTR_DRBG_MAX_INPUT) {
		ret = MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR;
		goto exit;
	}

	ret = 0;

exit:
	fclose(f);
	return (ret);
}

int mbedtls_ctr_drbg_update_seed_file(mbedtls_ctr_drbg_context *ctx, const char *path)
{
	FILE *f;
	size_t n;
	unsigned char buf[MBEDTLS_CTR_DRBG_MAX_INPUT];

	if ((f = fopen(path, "rb")) == NULL) {
		return (MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR);
	}

	fseek(f, 0, SEEK_END);
	n = (size_t)ftell(f);
	fseek(f, 0, SEEK_SET);

	if (n > MBEDTLS_CTR_DRBG_MAX_INPUT) {
		fclose(f);
		return (MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG);
	}

	if (fread(buf, 1, n, f) != n) {
		fclose(f);
		return (MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR);
	}

	fclose(f);

	mbedtls_ctr_drbg_update(ctx, buf, n);

	return (mbedtls_ctr_drbg_write_seed_file(ctx, path));
}
#endif							/* MBEDTLS_FS_IO */

#if defined(MBEDTLS_SELF_TEST)

static const unsigned char entropy_source_pr[96] = { 0xc1, 0x80, 0x81, 0xa6, 0x5d, 0x44, 0x02, 0x16,
													 0x19, 0xb3, 0xf1, 0x80, 0xb1, 0xc9, 0x20, 0x02,
													 0x6a, 0x54, 0x6f, 0x0c, 0x70, 0x81, 0x49, 0x8b,
													 0x6e, 0xa6, 0x62, 0x52, 0x6d, 0x51, 0xb1, 0xcb,
													 0x58, 0x3b, 0xfa, 0xd5, 0x37, 0x5f, 0xfb, 0xc9,
													 0xff, 0x46, 0xd2, 0x19, 0xc7, 0x22, 0x3e, 0x95,
													 0x45, 0x9d, 0x82, 0xe1, 0xe7, 0x22, 0x9f, 0x63,
													 0x31, 0x69, 0xd2, 0x6b, 0x57, 0x47, 0x4f, 0xa3,
													 0x37, 0xc9, 0x98, 0x1c, 0x0b, 0xfb, 0x91, 0x31,
													 0x4d, 0x55, 0xb9, 0xe9, 0x1c, 0x5a, 0x5e, 0xe4,
													 0x93, 0x92, 0xcf, 0xc5, 0x23, 0x12, 0xd5, 0x56,
													 0x2c, 0x4a, 0x6e, 0xff, 0xdc, 0x10, 0xd0, 0x68
												   };

static const unsigned char entropy_source_nopr[64] = { 0x5a, 0x19, 0x4d, 0x5e, 0x2b, 0x31, 0x58, 0x14,
													   0x54, 0xde, 0xf6, 0x75, 0xfb, 0x79, 0x58, 0xfe,
													   0xc7, 0xdb, 0x87, 0x3e, 0x56, 0x89, 0xfc, 0x9d,
													   0x03, 0x21, 0x7c, 0x68, 0xd8, 0x03, 0x38, 0x20,
													   0xf9, 0xe6, 0x5e, 0x04, 0xd8, 0x56, 0xf3, 0xa9,
													   0xc4, 0x4a, 0x4c, 0xbd, 0xc1, 0xd0, 0x08, 0x46,
													   0xf5, 0x98, 0x3d, 0x77, 0x1c, 0x1b, 0x13, 0x7e,
													   0x4e, 0x0f, 0x9d, 0x8e, 0xf4, 0x09, 0xf9, 0x2e
													 };

static const unsigned char nonce_pers_pr[16] = { 0xd2, 0x54, 0xfc, 0xff, 0x02, 0x1e, 0x69, 0xd2,
												 0x29, 0xc9, 0xcf, 0xad, 0x85, 0xfa, 0x48, 0x6c
											   };

static const unsigned char nonce_pers_nopr[16] = { 0x1b, 0x54, 0xb8, 0xff, 0x06, 0x42, 0xbf, 0xf5,
												   0x21, 0xf1, 0x5c, 0x1c, 0x0b, 0x66, 0x5f, 0x3f
												 };

static const unsigned char result_pr[16] = { 0x34, 0x01, 0x16, 0x56, 0xb4, 0x29, 0x00, 0x8f,
											 0x35, 0x63, 0xec, 0xb5, 0xf2, 0x59, 0x07, 0x23
										   };

static const unsigned char result_nopr[16] = { 0xa0, 0x54, 0x30, 0x3d, 0x8a, 0x7e, 0xa9, 0x88,
											   0x9d, 0x90, 0x3e, 0x07, 0x7c, 0x6f, 0x21, 0x8f
											 };

static size_t test_offset;
static int ctr_drbg_self_test_entropy(void *data, unsigned char *buf, size_t len)
{
	const unsigned char *p = data;
	memcpy(buf, p + test_offset, len);
	test_offset += len;
	return (0);
}

#define CHK(c)    if ((c) != 0)                          \
{                                       \
if (verbose != 0)                  \
mbedtls_printf("failed\n");  \
return (1);                        \
}

/*
 * Checkup routine
 */
int mbedtls_ctr_drbg_self_test(int verbose)
{
	mbedtls_ctr_drbg_context ctx;
	unsigned char buf[16];

	mbedtls_ctr_drbg_init(&ctx);

	/*
	 * Based on a NIST CTR_DRBG test vector (PR = True)
	 */
	if (verbose != 0) {
		mbedtls_printf("  CTR_DRBG (PR = TRUE) : ");
	}

	test_offset = 0;
	CHK(mbedtls_ctr_drbg_seed_entropy_len(&ctx, ctr_drbg_self_test_entropy, (void *)entropy_source_pr, nonce_pers_pr, 16, 32));
	mbedtls_ctr_drbg_set_prediction_resistance(&ctx, MBEDTLS_CTR_DRBG_PR_ON);
	CHK(mbedtls_ctr_drbg_random(&ctx, buf, MBEDTLS_CTR_DRBG_BLOCKSIZE));
	CHK(mbedtls_ctr_drbg_random(&ctx, buf, MBEDTLS_CTR_DRBG_BLOCKSIZE));
	CHK(memcmp(buf, result_pr, MBEDTLS_CTR_DRBG_BLOCKSIZE));

	mbedtls_ctr_drbg_free(&ctx);

	if (verbose != 0) {
		mbedtls_printf("passed\n");
	}

	/*
	 * Based on a NIST CTR_DRBG test vector (PR = FALSE)
	 */
	if (verbose != 0) {
		mbedtls_printf("  CTR_DRBG (PR = FALSE): ");
	}

	mbedtls_ctr_drbg_init(&ctx);

	test_offset = 0;
	CHK(mbedtls_ctr_drbg_seed_entropy_len(&ctx, ctr_drbg_self_test_entropy, (void *)entropy_source_nopr, nonce_pers_nopr, 16, 32));
	CHK(mbedtls_ctr_drbg_random(&ctx, buf, 16));
	CHK(mbedtls_ctr_drbg_reseed(&ctx, NULL, 0));
	CHK(mbedtls_ctr_drbg_random(&ctx, buf, 16));
	CHK(memcmp(buf, result_nopr, 16));

	mbedtls_ctr_drbg_free(&ctx);

	if (verbose != 0) {
		mbedtls_printf("passed\n");
	}

	if (verbose != 0) {
		mbedtls_printf("\n");
	}

	return (0);
}
#endif							/* MBEDTLS_SELF_TEST */

#endif							/* MBEDTLS_CTR_DRBG_C */
